HERBICIDE RESISTANT PLANTS

Abstract: Disclosed are plants, plant tissue and plant seed, whose growth and development are tolerant of, or resistant to various imidazole and triazole herbicidal compounds, at levels which normally are inhibitory to the plants. The tolerance or resistance is conferred by an altered imidazoleglycerol phosphate dehydratase (IGPD). Plant genes encoding wild-type and altered IGPD, purified plant IGPD, methods of isolating IGPD from plants, and methods of using both purified IGPD and IGPD-encoding genes are also disclosed.

Description: HERBICIDE RESISTANT PLANTS The invention relates generally to agricultural biotechnology. More specifically, it relates to herbicide resistance in plants, plant tissues and seeds. The use of herbicides to control weeds or plants in crops has become almost a universal practice. The relevant market exceeds a billion dollars annually. Despite this extensive use, weed control remains a significant and costly problem for farmers. Effective use of herbicides requires sound management. For instance, time and method of application and stage of weed plant development are critical in getting good weed control with herbicides. Since various weed species are resistant to herbicides, the production of effective herbicides becomes increasingly important. Unfortunately, herbicides that exhibit greater potency, broader weed spectrum and more rapid degradation in soil often have greater crop phytotoxicity. Crop hybrids or varieties resistant to or tolerant of the herbicides would allow for the use of the herbicides without attendant risk of damage to the crop. U.S. 4,761,373 to Anderson et al. is directed to plants resistant to various imidazolinone or sulfonamide herbicides. The resistance is conferred by an altered acetohydroxyacid synthase (AHAS) enzyme. U.S. 4,975,374 to Goodman et al. relates to plant cells and plants containing a gene encoding a mutant glutamine synthetase (GS) resistant to inhibition by herbicides that were known to inhibit GS, e.g. phosphinothricin and methione sulfoximine. U.S. 5,013,659 to Bedbrook et al. is directed to plants that express a mutant acetolactate synthase which renders the plants resistant to inhibition by sulfonylurea herbicides. U.S. 5,162,602 to Somers et al. discloses plants tolerant to inhibition by cyclohexanedione and aryloxyphenoxypropanoic acid herbicides. The tolerance is conferred by an altered acetyl coenzyme A carboxylase(ACCase). To genetically engineer plants for the purpose of herbicide resistance, the target of the herbicide first must be identified. This task can be very difficult. For example, the genome of R__ coli is capable of expressing at least 60 amino acid biosynthetic enzymes. Plants are much more complex, and thus contain many more enzymes. The sheer number of potential targets, therefore, is a factor. Also, plant enzymes have proven difficult to purify, which hinders large-scale in vitro screening efforts. Further, the effect of a herbicide on a particular plant enzyme cannot necessarily be predicted on the basis of the effect of the herbicide on the microbial analogue. Various herbicides, e.g. aminotriazoles, affect different biosynthetic pathways in plants and microbes. See, Hilton et al., Arch. Biochem. Biophys. 112:544-547 (1965); Jeim and Larrinua, Plant Physiol. 91:1226-1231 (1989). Finally, plants have other resistance mechanisms such as rapid metabolism, and poor uptake and translocation of the herbicide which complicates elucidation of the enzyme target. Within the scope of the present invention imidazoleglycerol phosphate dehydratase (IGPD) has been purified from a plant, and was found to be sensitive to various herbicides. Further cDNAs from plants have been isolated which encode IGPD. In accordance with these discoveries, the present invention provides plants, plant tissues and plant seeds resistant to, or tolerant of inhibition by an imidazole or triazole herbicide, or mixtures thereof, wherein the resistance is conferred by an altered IGPD resistant to or tolerant of inhibition by the herbicide at levels which normally inhibit the activity of IGPD in natively expressed amounts. Plants encompassed by the invention include those which would be potential targets for the herbicides, particularly agronomically important crops such as maize and other cereal crops such as wheat, oats, rye, sorghum, rice, barley, millet, turf and forage grasses, and the like, as well as cotton, sugar cane and soybeans. The present invention is directed further to methods for the production of plants, plant tissues, and plant seeds which contain an IGPD enzyme resistant to, or tolerant of inhibition by an imidazole or triazole herbicide at a concentration which normally inhibits the activity of IGPD in natively expressed amounts. One particular embodiment of the invention is directed to the preparation of transgenic maize plants, maize tissue or maize seed which have been stably transformed with a recombinant DNA molecule comprising a suitable promoter functional in plants operably linked to a structural gene encoding wild-type IGPD. This results in over-expression of the wild-type IGPD in the maize plant sufficient to overcome inhibition of the enzyme by the herbicide. The present invention also embodies the production of plants which express an altered IGPD enzyme tolerant of or resistant to inhibition by an imidazole or triazole herbicide at a concentration which normally inhibits the activity of wild-type, unaltered IGPD. In this embodiment, the plant may be stably transformed with a recombinant DNA molecule comprising a structural gene encoding the resistant IGPD, or prepared by direct selection techniques whereby herbicide resistant lines are isolated, characterized and developed. The present invention is also directed to processes for making and using IGPD. In particular, the present invention provides methods of using purified, wild-type IGPD to screen for novel herbicides which affect the activity of IGPD, and to identify herbicide-resistant IGPD mutants. Genes encoding altered IGPD can be used as selectable markers in plant cell transformation methods. The present invention is directed to plants, plant tissue and plant seeds resistant to or tolerant of imidazole and triazole herbicides, or mixtures thereof, wherein the resistance or tolerance is conferred by an altered IGPD enzyme. IGPD [EC 4.2.1.19] catalyzes the dehydration of imidazoleglycerol phosphate (IGP) to imidazoleacetol phosphate (IAP). This reaction occurs in the histidine biosynthetic pathway. Representative plants include any plants to which these herbicides are applied for their normally intended purpose. Preferred are agronomically important crops, i.e., angiosperms and gymnosperms significant as cotton, soybean, rape, maize, rice, wheat, barley, oats, rye, sorghum, millet, turf, forage grasses and the like. The term "imidazole herbicide" encompasses the imidazole represented by formula I, below, and any derivative of formula I that exhibits herbicidal activity; that is, it inhibits the growth, metabolism or replication of plant cells or whole plants. wherein R' represents hydrogen or flourine, or an -O-L group wherein L represents hydrogen, and R" represents a -SCH2CH3 or a -SCH2CH2OH group. The term "triazole herbicide" encompasses herbicidal chemical compounds represented by formula II, below, and derivatives thereof which exhibit herbicidal activity as defined above. B F G l 1 1 A -C - C - C - (0) 2 - K (TT I I I ' D D * H wherein A is a substituent group represented by: wherein W\ is hydrogen, C1-C4 alkyl or C2-C4 alkenyl; B is hydrogen, C1-C4 alkyl or -CH2OH; D and D' independently represent hydrogen or hydroxy, with the proviso that only one of D and D' can be hydroxy; F and G independently represent C1-C4 alkyl; or wherein B and G together represent -(CH3)-; n is 0 or 1; and K is P(O)(OR2)2» wherein R2 represents hydrogen or an alkali metal, alkaline earth metal, ammonium or an organic ammonium cation. Levels of imidazole and triazole herbicide which normally are inhibitory to the activity of IGPD include application rates known in the art, and which depend partly on external factors such as environment, time and method of application. For example, in the case of the triazole herbicides represented by formulae (II), the application rates range from 0.0001 to 10 kg/ha, preferably from 0.005 to 2 kg/ha. This dosage rate or concentration of herbicide may be different, depending on the desired action, and can be determined by methods known in the art. By "altered IGPD enzyme", it is meant increased expression of wild-type, herbicide-sensitive enzyme, or expression of a mutant, herbicide-tolerant IGPD. The "increased expression" results in a level of IGPD in the plant cell at least sufficient to overcome growth inhibition caused by the herbicide. The level of expressed IGPD generally is at least two times, preferably five times, and more preferably at least ten times the natively expressed amount. Thus, increased expression may be due to multiple copies of a wild-type IGPD gene; multiple occurrences of the IGPD coding sequence within the IGPD gene, i.e. gene amplification; or a mutation in the non-coding, regulatory sequence of the endogenous IGPD gene in the plant cell. Plants containing such altered IGPD enzyme can be obtained by direct selection. This method is known in the art. See, e.g. Somers et al. in U.S. 5,162,602, and Anderson et al. in U.S. 4,761,373, and references cited therein. These plants also may be obtained via genetic engineering techniques known in the art. Increased expression of herbicide-sensitive IGPD also can be accomplished by stably transforming a plant cell with a recombinant or chimeric DNA molecule comprising a promoter capable of driving expression of an associated structural gene in a plant cell, operatively linked to a homologous or heterologous structural gene encoding IGPD. By "homologous," it is meant that the IGPD gene is isolated from an organism taxonomically identical to the target plant cell. By "heterologous," it is meant that the IGPD gene is obtained from an organism taxonomically distinct from the target plant cell. IGPD genes can be obtained by complementing a bacterial or yeast auxotrophic mutant with a plant cDNA library. See, e.g. Snustad et al, Genetics 120:1111-1114 (1988) (maize glutamine synthase); Delauney et al., Mol. Genet. 221:299-305 (1990) (soybean -pyrroline -5-carboxylate reductase); Frisch et al., Mol. Gen. Genet. 228:287-293(1991) (maize dihydrodipicolinate synthase); Eller et al., Plant Mol. Biol. 18:557-566 (1992) (rape chloroplast 3-isopropylmalate dehydrogenase); Elledge et al, Proc. Natl. Acad. Sci, USA 88:1731-1735 (1991); Minet et al., Plant J. 2:417-422 (1992) (dihydroorotate dehydrogenase) and references cited therein. Other known methods include screening genomic or cDNA libraries of higher plants, for example, for sequences that cross-hybridize with specific nucleic acid probes, or by screening expression libraries for the production of IGPD enzymes that cross-react with specific antibody probes. A preferred method involves complementing an E. coli his B auxotrophic mutant with an Arabidopsis thaliana cDNA library. The term "altered IGPD enzyme" as used herein also encompasses mutant herbicide-resistant or herbicide-tolerant IGPD. Genes encoding such enzymes can be obtained by numerous strategies known in the art. A first general strategy involves direct or indirect mutagenesis procedures on microbes or tissue cultures of all types, seeds or plants. For instance, a genetically manipulable microbe, e.g. R coli or S. cerevisiae. may be subjected to random mutagenesis in vivo, with, for example UV light or ethyl or methyl methane sulfonate. Mutagenesis procedures are described, for example in Miller, Experiments in Molecular Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1972); Davis et al., Advanced Bacterial Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1980); and Sherman et al., Methods in Yeast Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1983). The microbe selected for mutagenesis contains an IGPD gene, the sequence of which is known. The mutagenized cells are grown in the presence of normally inhibitory concentrations of the inhibitor. DNA is prepared from colonies that display resistance or tolerance to the inhibitor; the IGPD genes from these colonies constitute further embodiments of the present invention. They are isolated, either by cloning or by polymerase chain reaction amplification, and their sequences are determined. Putatively mutant IGPD genes are tested for their ability to confer inhibitor resistance or tolerance on wild-type cells upon transformation. A second method of obtaining mutant herbicide-resistant or herbicide-tolerant alleles of IGPD involves direct selection in plants. For example, the effect of an IGPD inhibitor such as those described above, on the growth inhibition of plants such as Arabidopsis, may be determined by plating seeds sterilized by art-recognized methods on plates on a simple minimal salts medium containing increasing concentrations of the inhibitor. Such concentrations are in the range of 1, 3, 10, 30, 110, 330, 1000 and 3300 parts per million (ppm). The lowest dose at which significant growth inhibition can be reproducibly detected is used for subsequent experiments. Ethyl methane sulfonate (EMS) mutagenized M2 seeds (Lehle Seeds, Tucson, AZ), i.e. progeny seeds of plants grown from seeds mutagenized with ethyl methane sulfonate, are plated at densities of up to 10,000 seeds/plate (10 cm diameter) on minimal salts medium containing an appropriate concentration of inhibitor to select for resistance. Seedlings that continue to grow and remain green 7-21 days after plating are transplanted to soil and grown to maturity and seed set. Progeny of these seeds are tested for resistance or tolerance to the herbicide. Assuming the resistance is dominant, plants whose seed segregate 3:l::resistant:sensitive are presumed to have been heterozygous for the resistance at the M2 generation. Plants that give rise to all resistant seed are presumed to have been homozygous for the resistance at the M2 generation. Two approaches can be taken to confirm that the genetic basis of the resistance or tolerance is an altered IGPD gene. First, given the sequence of the Arabidopsis cDNA shown in Table 1 below (SEQ ID NO: 1), new alleles of the IGPD gene that putatively result in resistance to the inhibitor can be isolated using PCR. After sequencing the alleles to determine the presence of mutations in the coding sequence, the alleles can be tested for their ability to confer resistance to the inhibitor on plants into which the putative resistance-conferring alleles have been transformed. These plants can be either Arabidopsis - 1 - plants or any other plant whose growth is susceptible to the inhibitors. Second, the IGPD genes can be mapped relative to known restriction fragment length polymorphisms (RFLPs). See, for example, Chang et al. Proc. Natl. Acad, Sci, USA 85:6856-6860 (1988); Nam et al., Plant Cell L699-705 (1989). The resistance trait can be independently mapped using the same markers. If the resistance maps to a position indistinguishable from one of the IGPD gene's position, it is likely the result of a mutation in that IGPD gene. A third method of obtaining inhibitor-resistant or inhibitor-tolerant alleles of IGPD is by selection in plant cell cultures. Actively growing callus or suspension cultures of a plant of interest are grown on defined medium lacking histidine in the presence of increasing concentrations of the inhibitor. Varying degrees of growth are recorded in different cultures. In certain cultures, fast-growing variant colonies arise that continue to grow even in the presence of normally inhibitory concentrations of inhibitor. Putative resistance-conferring alleles of the IGPD gene are isolated and tested as described in the foregoing paragraphs. A fourth method involves mutagenesis of wild-type, herbicide sensitive IGPD genes in bacteria or yeast, followed by culturing the microbe on medium that lacks histidine, but which contains inhibitory concentrations of the inhibitor, and then selecting those colonies that grow in the presence of the inhibitor. More specifically, a plant cDNA, such as the Arabidopsis cDNA encoding IGPD is cloned into a microbe that otherwise lacks IGPD activity. Examples of such microbes include E. coli or S. cerevisiae auxotrophic mutants. The transformed microbe is then subjected to in vivo mutagenesis such as described immediately above, or to in vitro mutagenesis by any of several chemical or enzymatic methods known in the art, e.g. sodium bisulfite (Shortle et al., Methods Enzymol. 100:457-468 (1983); methoxylamine (Kadonaga et al., Nucleic Acids Res. 13:1733-1745 (1985); oligonucleotide-directed saturation mutagenesis (Hutchinson et al., Proc. Natl. Acad. Sci. USA, 83:710-714 (1986); or various polymerase misincorporation strategies (see, e.g. Shortle et al., Proc. Natl. Acad. Sci. USA, 79:1588-1592 (1982); Shiraishi et al., Gene 64:313-319 (1988); and Leung et al., Technique LI 1-15 (1989). Colonies that grow in the presence of normally inhibitory concentrations of inhibitor are picked and purified by repeated restreaking. Their plasmids are purified and tested for the ability to confer resistance to or tolerance of the inhibitor by retransforming them into the IGPD-lacking microbe. The DNA sequences of IGPD cDNA inserts from plasmids that pass this test are then determined. Examples of promoters capable of functioning in plants or plant cells, i.e., those capable of driving expression of the associated structural genes such as IGPD in plant cells, include the cauliflower mosaic virus (CaMV) 19S or 35S promoters and CaMV double promoters; nopaline synthase promoters; pathogenesis-related (PR) protein promoters; small subunit of ribulose bisphosphate carboxylase (ssuRUBISCO) promoters, ubiquitine promoters, actin promoters, histone promoters, tubulin promoters and the like. Preferred are the 35S promoter and an enhanced or double 35S promoter such as that described in Kay et al., Science 236: 1299-1302 (1987), incorporated herein by reference, and the double 35S promoter cloned into pCGN2113 and deposited as ATCC 40587 as disclosed in example 23 of EP-392 225. The promoters themselves may be modified to manipulate promoter strength to increase IGPD expression, in accordance with art-recognized procedures. The expression signals may also comprise tissue-preferential or tissue specific promoters. The term tissue-preferential promoter is used to indicate that the given expression signal will promote a higher level of transcription of the associated expressible DNA, or of expression of the encoded product as indicated by any conventional RNA or protein assay, or that a given DNA sequence will demonstrate some differential effect; i.e., that the transcription of the associated DNA sequences or the expression of a gene product is greater in some tissue than in all other tissues of the plant. For example, the tissue-preferential promoter may direct higher expression of the IGPD gene product in leaves, stems, roots and/or pollen than in seed. One example of a tissue-preferential promoter, which may be suitably used within the scope of the present invention, is a pith-preferred promoter isolated from a maize TrpA gene. The term tissue-specific promoter is used to indicate that a given regulatory DNA sequences will promote transcription of an associated expressible DNA sequence entirely in one or more tissues of a plant, or in one type of tissue, e.g. green tissue, while essentially no transcription of that associated coding DNA seuquence will occur in all other tissues or types of tissues of the plant. Numerous promoters the expression of which is known to vary in a tissue specific manner are known in the art. One such example is the maize phosphenol pyruvate carboxylase (PEPC), which is green tissue-specific (Hudspeth et al, Plant Mol Biol 12:579-589, 1989). Other green tissue-specific promoters include chlorophyll a/b binding protein promoters and RubisCo small subunit promoters. Further to be mentioned here are, for example, pollen-specific promoters such as those obtainable from a plant calcium-dependent phosphate kinase (CDPK) gene. A developmentally regulated promoter can also be used. Of course, in the present invention, any promoter which is functional in the desired host plant can be used to direct the expression of the associated IGPD gene. It is often advantageous to incorporate a leader sequence between the promoter sequence and the adjacent coding DNA sequence, the length of the leader sequence being so selected that the distance between the promoter and the DNA sequence according to the invention is the optimum distance for expression of the associated structural gene. Further regulatory DNA sequences that may be used for the construction of chimaeric genes include, for example, sequences that are capable of regulating the transcription of an associated DNA sequence in plant tissues in the sense of induction or repression. There are, for example, certain plant genes that are known to be induced by various internal and external factors, such as plant hormones, heat shock, chemicals, pathogens, oxygen deficiency, light, stress, etc.. Another class of genes that are inducible in plants comprises the light-regulated genes, especially the nuclear-coded gene of the small subunit of ribulose-l,5-biphosphate carboxylase (RUBISCO). Morelli et al, Nature 3 5: 200-204 (1985) have shown that the 5 '-flanking sequence of a RUBISCO gene from the pea is capable of transferring light-inducibility to a reporter gene, provided the latter is linked in chimaeric form to that sequence. It has also been possible to extend this observation to other light-induced genes, for example the chlorophyll-a/b-binding protein. A further group of regulatable DNA sequences comprises chemically regulatable sequences that are present, for example, in the PR (pathogenesis-related) protein genes of tobacco and are inducible by means of chemical regulators such as those described in EP-A 332,104. The regulatable DNA sequences mentioned by way of example above may be of both natural or synthetic origin, or they may comprise a mixture of natural and synthetic DNA sequences. The chimeric DNA construct(s) of the invention may contain multiple copies of a promoter or multiple copies of the IGPD structural genes. In addition, the construct(s) may include coding sequences for markers and coding sequences for other peptides such as signal or transit peptides, each in proper reading frame with the other functional elements in the DNA molecule. The preparation of such constructs are within the ordinary level of skill in the art. Useful markers include peptides providing herbicide, antibiotic or drug resistance, such as, for example, resistance to hygromycin, kanamycin, G418, gentamycin, lincomycin, methotrexate, glyphosate, phosphinothricin, or the like. These markers can be used to select cells transformed with the chimeric DNA constructs of the invention from untransformed cells. Other useful markers are peptidic enzymes which can be easily detected by a visible reaction, for example a color reaction, for example luciferase, β-glucuronidase, or β-galactosidase. Signal or transit peptides provide the IGPD formed on expression of the chimeric DNA constructs of the invention with the ability to be transported to the desired site of action. Examples of signal peptides include those natively linked to the plant pathogenesis-related proteins, e.g. PR-1, PR-2, and the like. See, e.g., Payne et al., Plant Mol. Biol. Ll:89-94 (1988). Examples of transit peptides include the chloroplast transit peptides such as those described in Von Heijne et al., Plant Mol. Biol. Rep. 9:104-126 (1991), and mitochondrial transit peptides such as those described in Boutry et al., Nature 328:340-342 (1987). Also included are sequences that result in localization of the encoded protein to various cellular compartments such as the vacuole. See, for example, Neuhaus et al., Proc. Natl. Acad. Sci. USA 88: 10362-10366 (1991), EP-462 065, and Chrispeels, Ann. Rev. Plant Physiol. Plant Mol. Biol. 42: 21-53 (1991). The relevant disclosures of these publications are incorporated herein by reference in their entirety. The recombinant DNA molecules can be introduced into the plant cell in a number of art-recognized ways. Those skilled in the art will appreciate that the choice of method might depend on the type of plant, i.e. monocot or dicot, targeted for transformation. Suitable methods of transforming plant cells include microinjection (Crossway et al., BioTechniques 4:320-334 (1986)), electroporation (Riggs et al, Proc. Natl. Acad. Sci. USA 83:5602-5606 (1986), Agrobacterium mediated transformation (Hinchee et al., Biotechnology 6:915-921 (1988)), direct gene transfer (Paszkowski et al., EMBO J. 3:2717-2722 (1984)), and ballistic particle acceleration using devices available from Agracetus, Inc., Madison, Wisconsin and Dupont, Inc., Wilmington, Delaware (see, for example, Sanford et al., U.S. Patent 4,945,050; and McCabe et al., Biotechnology 6:923-926 (1988)). Also see, Weissinger et al., Annual Rev. Genet 22:421-477 (1988); Sanford et al., Paniculate Science and Technology 5:27-37 91987)(onion); Christou et al., Plant Physiol. 87:671-674 (1988)(soybean); McCabe et al., Bio/Technology 6:923-926 (1988)(soybean); Datta et al., Bio/Technology 8:736-740 (1990)(rice); Klein et al., Proc. Natl. Acad. Sci. USA, 85:4305-4309 (1988)(maize); Klein et al., Bio/Technology 6:559-563 (1988)(maize); Klein et al., Plant Physiol. £1:440-444 (1988)(maize); Fromm et al., Bio/Technology 8:833-839 (1990); and Gordon-Kamm et al., Plant Cell 2:603-618 (1990)(maize); Svab et al. Proc. Natl. Acad. Sci. USA 87:8526-8530 (1990) (tobacco chloroplast). Genes encoding altered IGPD resistant to or tolerant of an IGPD inhibitor can be used as selectable markers in a method of selecting plants, plant tissue or plant cells transformed with a transgene of interest from non-transformed plants, comprising the steps of: (a) transforming a plant, plant tissue or plant cell with a gene encoding an altered IGPD resistant to an IGPD inhibitor; (b) transferring the thus-transformed plants or plant cells to a medium comprising the IGPD inhibitor; and (c) selecting the plants or plant cells which survive in the medium. For example, plants, plant tissues or plant cells can be co-transformed with a transgene of interest and a gene encoding an altered IGPD capable of being expressed in the plant as a selectable marker. The thus-transformed cells are transferred to medium containing the IGPD inhibitor wherein only the transformed cells will survive. The method is applicable to any plant cell capable of being transformed with an altered IGPD-encoding gene, and can be used with any transgene of interest. Expression of the transgene and the IGPD gene can be driven by the same promoter functional on plant cells, or by separate promoters. Another embodiment of the present invention is directed to substantially purified IGPD, preferably plant IGPD and most preferably wheat IGPD. IGPD can be prepared by isolating crude IGPD from plant material and then purifying the thus obtained extract. The purification of plant enzymes from plant material has been difficult, primarily due to the low amounts of the enzymes in plants. In the case of IGPD, the situation was exacerbated since standard assays used in previous studies were unreliable. Thus, in many plants, IGPD activity was undetectable. Specifically, the direct determination of enolized IAP (imidazoleacetol phosphate) in strong alkali at 280 nm, described in Ames, J. Biol. Chem. 228:131-143 (1957) which was used in all previously reported studies, was not applicable in crude plant extracts and slightly enriched enzyme preparations due to a high background absorbance inherent to such plant preparations. Within the present invention it has been found that an alternative method which involves measuring the amount of imidazoleacetol (IA) produced from the enzymatic hydrolysis of synthetic IAP in the presence of alkaline phosphatase and alkali, rather than HC1, by determining the absorption of its enolized form in alkali at 370 nm, provides a more sensitive method adequate to detect previously undetectable IGPD in plants. The starting material, e.g. crude enzyme extract, can be prepared in accordance with known techniques. Likewise, purification of the crude IGPD extract can be accomplished by adequately combining art-recognized procedures. See, Scopes, Protein Purification: Principles and Practice, 2nd Ed., Springer- Verlag (New York, 1987). In general, a combination of purification techniques such as fractionation and chromatography is preferred to obtain pure IGPD. By "pure," it is meant a substantially homogeneous IGPD preparation. Preferred purification schemes include combinations of techniques such as ammonium sulfate fractionation, hydrophobic chromatography, affinity chromatography, ion-exchange chromatography and FPLC chromatography. The determination of specific purification schemes will depend primarily on the degree of purification sought and the particular starting material used. A specifically preferred purification technique involves the use of a ligand capable of binding IGPD in affinity chromatography. A preferred ligand is the compound represented by formula (III): A column of a filtration gel or matrix may be prepared using standard techniques. A preferred column is prepared of thiopropyl Sepharose 6B and is then washed with 5 mM DTT in buffer A (20 mM NaPB / 1 mM EDTA at pH 7.4). The ligand is applied to the column at a predetermined concentration, e.g., 60 μmol in buffer A, and the effluent is reapplied to the top of the column and recirculatization is continued overnight. The column may be subsequently washe with buffer A containing 1 M NaCl. The sample from which IGPD is to be purified is added to the affinity column at a predetermined flow rate, e.g. 8 ml/hr, and the column is then washed with buffer A and then with 10 mM Tris-HCl at pH 7 befor elution of the IGPD by the addition of a solution, e.g., 1 M aminotriazol, which allows the desorption of IGPD. Those skilled in the art will appreciate that specific parameters and reagents may be varied accordingly. This embodiment of the present invention encompasses IGPD isolated from any higher plant. Preferred sources of IGPD include wheat, maize, rye, sorghum, rice, barley, millet, turf and forage grasses, cabbage, and pea. In a more preferred embodiment, the IGPD is isolated from wheat germ, the preparation of which is set forth in Example 7, below. Wheat germ IGPD has a native molecular weight of from about 600,000 Dto about 670,000 D. The molecular weight is about 600,000 D as measured by Superdex G-200 gel filtration. A molecular weight of 670,000 D was determined by native PAGE. The enzyme is composed of at least 24 subunits, each with a molecular weight of 25,500 D. The subunits are associated non-covalently. The enzyme has a specific activity of about 5.7 U/mg of protein. The isoelectric point is about 5.65. The enzyme activity is stable up to about 30°C, but is decreased by about 50% when incubated for 40 minutes at 60°C. The enzyme remains stable, i.e. retains substantially all biological activity, when stored at -80°C for at least one month. The Km value of wheat germ IGPD for IGPD was determined as 0.4 mM. Maximal enzyme activity is at pH 6.6 as measured in 50mM Bis-Tris-propane-HCl buffer, containing 100 mM 2-mercaptoethanol and 1 mM MnCl2- Aminotriazole, a known competitive inhibitor of SL tvphimurium IGPD, inhibits wheat germ IGPD competitively with a Ki of about 46 μM at pH 6.6. The presence of manganese ions enhances the activity of the enzyme 7-fold at a concentration of 0.5 mM. The Km value for Mnr + is about 0.11. Similar to IGPD of N. crassa, S. tvphimurium and yeast, the wheat germ enzyme requires a reducing agent for activity. The wheat germ enzyme can be prepared by transforming a host cell with a DNA molecule represented by the sequence set forth in Table 3A (SEQ ID NO: 9), below, consistent with the teachings of the invention. Substantially purified IGPD also can be prepared via genetic engineering techniques known in the art using the IGPD cDNAs disclosed herein. In accordance with this method, a recombinant host cell stably transformed with a DNA molecule containing an IGPD structural gene, which cell is capable of expressing the gene, is cultivated under suitable conditions to allow the host cell to produce IGPD in predetermined quantities, and then the IGPD produced is isolated. The construction of chimeric DNA molecules is known in the art. The choice of specific regulatory sequences such as promoter, signal sequence, 5' and 3' untranslated sequences, and enhancer, is within the level of skill of the routineer in the art. The resultant molecule, containing the individual elements linked in proper reading frame, may be inserted into a vector capable of being transformed into the host cell. Examples include plasmids such as pBluescript (Stratagene, La Jolla, CA), pFLAG (International Biotechnologies, Inc., New Haven, CT), pTrcHis (Invitrogen, La Jolla, CA), and baculovirus expression vectors, e.g., those derived from the genome of Autographica californica nuclear polyhedrosis virus (AcMNPV) (Luckow and Summers, Bio/Technology 6:47-55 (1988)). A preferred baculovirus/insect system is pV111392/Sf21 cells (Invitrogen, La Jolla, CA). Other suitable hosts include microbes, preferably bacteria and most preferably E. coli and yeast. Purified IGPD may be used in a method of determining the inhibitory effect on IGPD of a chemical suspected of having such an effect, comprising the steps of; (a) adding a predetermined amount of the chemical to a predetermined volume of a reaction mixture comprising substantially purified IGPD; (b) adding IGP to the resultant mixture to initiate an enzyme reaction; (c) terminating the reaction after a predetermined time; (d) adding alkaline phosphatase and alkali to the mixture; and (e) measuring the amount of IA produced by determining the absorbance difference at 370nm at an absorbance coefficient of 10,400. Thus purified IGPD may be used in assays to discover novel inhibitors of the enzyme, which inhibitors potentially would function as commercially viable herbicides. Typically, the inhibitory effect of a chemical on IGPD is determined by the absorbance difference at 370 nm using an absorbance coefficient of 10,400, which signifies the production of IAP from IGP. See, Ames et al., J. Biol. Chem. 212:687-697 (1955). Inhibitor solutions in various concentrations, e.g. 1 mM, 100 μM, 10 μM, and 1 μM, are added to the reaction mixture prior to the initiation of the enzyme reaction. A representative reaction mixture contains 50 mM Bis-Tris-propane-HCl (pH 6.6), 100 mM 2-mercaptoethanol, 1 mM MnCl2, 1 mM IGP, and between 2 and 5 mU of IGPD. Once IGP is added, the reaction is run at 30°C, and is stopped by the addition of perchloric acid up to 10% volume of the reaction mixture. After centrifugation, the supernatant is adjusted to pH 10, e.g. by adding 1 M 2-ethylaminoethanol. Alkaline phosphatase and MgCl2 then are added to the mixture to final concentrations of 25 U/ml and 2.2 mM, respectively. The resultant mixture is incubated at 45°C for 20 minutes, whereafter the mixture is chilled, e.g. in salt-ice. Five volumes of 5N NaOH are added to the solution, and after two minutes, enolized IA is measured spectroscopically. One unit of enzyme activity is defined as the amount of enzyme catalyzing the formation of 1 μmol of IAP/imidazole acetol per minute under the assay conditions. If a measure of inhibition greater than μM is expected, the assays may be repeated using even lower concentrations of inhibitor. Another embodiment of the present invention involves the use of IGPD in an assay to identify inhibitor-resistant or inhibitor-tolerant IGPD mutants. A typical assay is as follows: (a) incubating wild-type IGPD and its substrate, IGP in the presence of an inhibitor of wild-type IGPD; (b) measuring the activity of wild-type IGPD in step (a); (c) incubating mutated IGPD and its substrate, IGP in the presence of an inhibitor of wild-type IGPD; (d) measuring the activity of mutated IGPD in step (c); and (e) comparing the activity of wild-type IGPD determined in step (b) to the activity of mutated IGPD determined in step (d). The reaction mixture and the reaction conditions are the same as for the assay to identify inhibitors of IGPD (inhibitor assay) with the following modifications. First, an IGPD mutant, obtained as described above, is substituted in one of the reaction mixtures for the wild-type IGPD of the inhibitor assay. Second, an inhibitor of wild-type IGPD is present in both reaction mixtures. Third, mutated activity (enzyme activity in the presence of inhibitor and mutated IGPD) and unmutated activity (enzyme activity in the presence of inhibitor and wild-type IGPD) are compared to determine whether a significant increase in enzyme activity is observed in the mutated activity when compared to the unmutated activity. Mutated activity is any measure of enzymatic activity of the mutated IGPD enzyme while in the presence of a suitable substrate and an inhibitor of the wild-type IGPD enzyme. Unmutated activity is any measure of enzymatic activity of the wild-type IGPD enzyme while in the presence of a suitable substrate and an inhibitor of the wild-type IGPD enzyme. A significant increase is defined as an increase in enzymatic activity that is larger than the margin of error inherent in the measurement technique, preferably an increase by about 2-fold of the activity of the wild-type enzyme in the presence of the inhibitor, more preferably an increase by about 5-fold, most preferably an increase greater than by about 10-fold. The invention will be further described by reference to the following detailed examples. These examples are provided for purposes of illustration only, and are not intended to be limiting unless otherwise specified. EXAMPLES Example 1: Isolation of plant cDNAs that complement an E. coli hisB mutant A cDNA library of polyA(+) RNA from Arabidopsis thaliana ecotype Columbia (Lehle Seeds, Tucson, AZ) was constructed in the bacteriophage vector lambda ZAP II (Stratagene Cloning Systems, La Jolla, CA) using the Uni-ZAP XR Gigapack II Gold cloning kit (Stratagene) as described by the manufacturer. Filamentous phagemids containing the cDNA inserts were excised from an amplified aliquot of the library using the helper phage R408 as described in the manufacturer's instructions (Stratagene). Escherichia coli strain SB3930 (CGSC #4930) was obtained from the E. coli Genetic Stock Center (New Haven, CT). SB 3930 carries the hisB463 allele, which contains a specific lesion in IGPD dehydratase activity. SB3930 was rendered male by mating with coli strain K603 (CGSC # 6451). K603 is auxotrophic for leucine, threonine, and tryptophan, and harbors Fl::TnlO, which confers tetracycline resistance (tetR). TetR, leu+, thr+, trp+ transconjugants were selected, and tested for histidine auxotrophy. The resulting strain was named STL A 90 μl aliquot of the cDNA library phagemid stock (2.1 x 10" transducing units/ml) was infected into 2.2 ml of a mid-log phase culture of strain ST The mixture was allowed to incubate at 37°C for 15 minutes, then pelleted and washed in minimal Vogel-Bonner VB medium (Vogel and Bonner, J. Biol. Chem. 218:97-106, 1956). The washed cells were plated on VB agar plates (containing ampicillin at 100 μg/ml [amplOO]) and incubated for two days at 37°C. None to several colonies were observed on each plate. Control, rich medium amplOO plates and VB + histidine plates each had an uncountable number of colonies (greater than 10,000 colonies/plate). The negative control of ST1 without phagemid infection resulted in no colonies on (VB) amp plates. The colonies resulting from phagemid infection were purified by repeated streaking on VB amplOO agar. The colonies were grown in liquid culture and their plasmids extracted by methods known to those skilled in the art. The purified plasmids were tested for their ability to transform ST1 to histidine prototrophy at high frequency. Two plasmids, designated pSTA3 and pSTA4, were isolated that reproducibly complement the hisB463 mutation. The Arabidopsis cDNA encoding IGPD contained in pSTA3 is set forth in Table 1 (SEQ ID NO: 1) below. TABLE 1 (SEQ ID NO: 1) 1 GTTCCTTCCG CTGCCAACAA AATGGAGCTG TCGTCTGCGT CCGCCATATT 51 AAGCCACTCC TCCTCCGCCG CTCAGCTTCT CAGACCTAAG CTCGGGTTTA 101 TTGATTTGCT TCCTCGTCGA GCGATGATCG TTTCTTCTCC TTCTTCTTCG 151 CTTCCTCGAT TTTTGCGGAT GGAATCTCAA TCTCAGCTTC GCCAATCTAT 201 CTCTTGCTCT GCTTCTTCTT CTTCTTCTAT GGCATTAGGT AGAATTGGAG 251 AAGTAAAGAG AGTAACAAAG GAAACGAATG TTTCAGTGAA GATTAATTTG 301 GATGGTACTG GAGTTGCAGA TAGTTCTAGT GGAATTCCTT TCCTTGACCA 351 TATGTTAGAT CAACTTGCTT CGCATGGCTT GTTTGATGTG CACGTTAGAG 401 CTACTGGTGA TGTTCACATT GATGATCATC ACACTAATGA AGATATAGCT 451 CTTGCCATTG GAACTGCTCT ATTAAAGGCT CTTGGTGAGC GTAAAGGGAT 501 TAACCGGTTT GGTGACTTCA CAGCTCCTCT AGATGAAGCG CTTATACATG 551 TTTCCTTGGA CTTGTCTGGT CGACCATATC TTGGTTACAA CTTGGAGATA 601 CCAACTCAGA GAGTTGGAAC ATATGATACT CAGTTGGTGG AGCACTTTTT 651 CCAGTCGTTG GTGAATACTT CTGGTATGAC TCTTCACATT CGGCAGCTCG 701 CTGGTGAAAA CTCTCATCAC ATAATAGAGG CGACGTTTAA GGCGTTTGCC 751 AGAGCTCTAC GACAAGCAAC AGAGACTGAT CCACGCCGTG GTGGGACAAT 801 ACCAAGTTCA AAAGGAGTCT TATCACGGTC TTGAAAGCTA ATCAAACACA 851 CAAGACAGTT CCCAGATTCA CACTTCATCG TCGAGTTCAT GAGCCATCGT 901 CAATTCTCTT ATGGTACCAA ATGCCAAGCC TGTTGGATCT TGCTGTTCCA 951 TTCCATTACA GAAGCACAAA GAGCAAAATG TGAAAATAGA TTAGAGATCA 1001 CACAGTTCAG AAGATCATAG GCTCATCTTT ATATTAATCT GTTGTTGCAG 1051 AGTGTATTAA ACCTCTTACC ATTGCTGTAT CATCATCAAC TGAGAACTTA 1101 CTGTGAGTTG AAGTGACTGT AATTTGCTTT AAAAAAAAAA The cDNA sequence shown in Table 1 (SEQ ID NO: 1) was cloned into pBluescript, resulting in plasmid pSTA3. This plasmid is on deposit with the ATCC, 12301 Parklawn Drive, Rockville, MD 20852. The deposit was made on June 5, 1991, and accorded accession number ATCC 75014. The Arabidopsis cDNA depicted in Table 1 (SEQ ID NO: 1) is 1140 bp in length, and encodes a predicted protein of 271 amino acids, beginning with a methionine codon at nucleotide 22. The N-termius of the predicted protein has features similar to other chloroplast transit peptides, consistent with the apparent localization of the histidine biosynthetic pathway to the chloroplast. Nagai et al., Proc. Natl. Acad. Sci USA 88, 4133 (1991). A comparison of the predicted amino acid sequence to the sequences of hisB from R coli and HIS3 from ∑ . cerevisiae revealed a region of highly conserved sequence beginning at codon 73 of the predicted open reading frame of the cDNA. This codon was presumed to be the mature N terminus of IGPD, which was not experimentally determined because the N-terminus of the protein was blocked to Edman degradation. It was determined that the presumptive mature Arabidopsis IGPD protein sequence shares 52% identity with the gene product from E. coli and 45% identity with the HIS 3 gene product from yeast, as determined using the program GAP described in Deveraux et al., Nucleic Acids Res. 12, 387 (1984). A second cDNA encoding IGPD was isolated by screening a cDNA library made from Arabidopsis leaf tissue mRNA with the IGPD cDNA probe given as Table 1. Partial sequence analysis indicated that some clones were significantly homologous to the sequence of the originally isolated IGPD within the coding region (approximately 77% identical), typical of cDNAs derived from independent genes. The partial clone for the second cDNA was used to screen the cDNA library, and additional clones were isolated. The partial sequence of this clone is designated SEQ ID NO: 12. The plasmid pIGPDat.2 containing this partial sequence of a second IGPD cDNA from Arabidopsis was deposited on April 26, 1994 with the Agricultural Research Service, Patent Culture Collection (NRRL), Northern Regional Research Center, 1815 North University Street, Peoria, Illinois 61604, U.S.A. and was assigned accession number NRRL B- . Example 2: Confirmation of enzyme activity encoded by the plant cDNAs Extracts of soluble protein from E. coli strains ST1 (pSTA3), ST1, and XLl-Blue (Stratagene), a wild-type his+ control strain, were prepared as follows. The bacteria were grown overnight in rich medium or in the case of XLl-Blue, in VB medium, and collected by centrifugation. Approximately 0.5 - 1.0 g of cells were resuspended in 4 ml of 100 mM triethanolamine (pH 7.5), 100 mM 2-mercaptoethanol, 1 mM MnCl2 and broken by sonication in short pulses for 2-3 minutes. Cell debris was removed by centrifugation and proteins in the supernatant were precipitated by addition of (NH4)2SO4 to a concentration of 80% (w/v). The protein pellet was redissolved in the buffer described above and desalted by passage over a Sephadex G-25 column (Pharmacia, Piscataway, NJ). IGP was synthesized as described by Ames, J.Biol. Chem. 228:131-143 (1957), and purified as follows. Charcoal was added to the acidic eluate (pH 1.0) of the Dowex 50 column, the first purification step (Ames, 1957). The clear filtrate containing non-adsorbed IGP was neutralized with NaOH and applied on a charcoal column. Adsorbed IGP was eluted with 50% (v/v) methanol in 0.1 N HC1, lyophilized and dissolved in methanol. IGP was neutralized with propylenoxide containing an equimolar amount of water. The extracts were then assayed for IGPD activity by measuring imidazoleacetol (IA) obtained by hydrolyzing IAP as follows. The reaction mixture (total volume 125 μl) contained 50 mM Bis-Tris-propane-HCl buffer (pH 6.6), 100 mM 2-mercaptoethanol, 1 mM MnCl2, 1 mM IGP, and 100 μl of bacterial extract. The reaction was started by addition of the IGP substrate, and was incubated at 37°C and stopped after 60 minutes by adding 1/10 volume of 1 N perchloric acid. After centrifugation, the supernatant was adjusted to pH 10 with 1M 2-ethylaminoethanol. Alkaline phosphatase (Sigma, St. Louis, MO) and MgCl2 were added to the mixture to reach a final concentration of 25 U/ml and 2.2 mM, respectively. After incubation at 45°C for 20 minutes, the reaction mixture was chilled in a salt-ice bath. Five volumes of 5N NaOH were added to the solution, and after 2 minutes, the concentration of enolized IA was determined from the absorbance at 370 nm using the extinction coefficient of 10,400 (Ames and Mitchell, J. Biol. Chem. 212: 687-697(1955)). One unit of enzyme is defined as the amount that catalyzes the formation of lμmol of IAP per minute under the assay conditions described. Those skilled in the art will appreciate that reactants and reaction parameters of this assay, to the exception of alkaline phosphatase, can be varied without sacrificing sensitivity. Table 2 summarizes the data so obtained. STl was found to completely lack IGPD activity. XLl-Blue contained detectable IGPD activity. STl (pSTA3) had a comparable level of IGPD activity. TABLE 2 Mutant without Activity STl STl XLl-Blue STl (pSTA3) (pSTA4) 1. +Extract +IGP 0.197 -0.025 0.212 0.268 2. +Extract -IGP -0.020 0.002 -0.019 -0.016 3. boiled Extract +IGP -0.007 0.002 -0.015 -0.015 4. 1-2-3 (=ΔA37θ) 0.224 -0.029 0.246 0.299 specific activity μmol/mg/h 1.22xl0 '2 0 0.99xl0 "2 1.38x10- Extracts were assayed for IGPD activity by incubation with IGP and subsequent measurement of IA as described above. Values obtained for incubation without IGP (row 2) and with boiled extracts (row 3) were subtracted from the raw values in row 1 to give the values in row 4. STl was found to have no activity, whereas STl (pSTA3) and STl (pSTA4) had activities comparable to XLl-Blue. Example 3: Isolation of an IGPD cDNA from wheat A cDNA library was constructed as described above in Example 1 using wheat seedlings as starting material. The phage library was plated at a density of approximately 10,000 plaques on a 10 cm petri dish, and filter lifts of the plaques were made after overnight incubation of the plates at 37°C. The plaque lifts were probed with the Arabidopsis cDNA, labelled with 32P-dCTP by the random priming method by means of a PrimeTime kit (International Biotechnologies, Inc., New Haven, CT). Hybridization conditions were 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO4 pH 7.0, 1 mM EDTA at 50°C. After hybridization overnight, the filters were washed with 2X SSC, 1% SDS. Positively hybridizing plaques were detected by autoradiography at a frequency of approximately one in 10,000. After purification to single plaques, cDNA inserts were excised in vivo according to manufacturer's instructions (Stratagene, La Jolla, CA). Plasmid DNAs were purified using Magic Miniprep columns (Promega Biotech, Madison, WI), and their sequences determined by the chain termination method using dideoxy terminators labelled with fluorescent dyes (Applied Biosystems, Inc., Foster City, CA). Sequences of several clones were found to share approximately 70% identity with the DNA sequence of the Arabidopsis IGPD cDNA. The sequence originally determined for one apparently full length clone is set forth below in Table 3 in the antisense, or reverse complement, orientation (SEQ ID NO: 2). This sequence, with minor revisions incorporated after further sequence analysis, is set forth below in Table 3A in the sense orientation (SEQ ID NO: 9). TABLE 3 (SEQ ID NO: 2) 1 CCCCCCCTCG AGTTTTTTTT TTTTTTTTTT GGAGATTATT ATTCTATTTC 51 ATTTCACTCT TTTGAATGGC CAAACCATTA TTACAGGCGC AACACCGCGC 101 AAACCAATGC TGAATCCATA TATCAGAGGT AATAACTTTC AGAATGTCAA 151 GCCGTCTGCA GCTTTTACAT CTTCAGATGT AAGTGTTGTC CAGCAAAACT 201 GCAGTAGCGA GCAGATACAG TATGCCAATG GTAGTAAGAT AAACAAACCC 251 TGACAACAGG ATAACAAGCA ATTTCCATGC TGTTCTTGTT CCAAACCCCG 301 CGGACTGCAA GTCCAAGTAG CAGCAGAGAC ATAGCAGGCG ACCGCCCATG 351 TGTTTCTTTG AGGGCGAATA GCGTGCGTCC AGTTTTCGAT CTTGCATTGC 401 AACACTAAGA CCTTGACAGA ACACCTTTTG AGCTTGGCAT AGTGCCCTGG 451 CGGCGTAAGT CA ATTCCGT TGCTTGTCGA AGCGCCCTGG CAAATGCTTT 501 GAAGTTGCCT CGATAATATG GTGTGAGTTG TTTCCCGCAA GCTGACGGAT 551 GTGAAGCGTC ATGCCAGATG TATTCACAAG GGACTGGAAG AAATGCTCAA 601 CTAGCTGTGT GTCATATGTG CCAACTCTTT CGGTAGGAAT GCTTAAGCCG 651 CAGCTCAAAT GAGGTCGACC AGATAGATCC AGTATAACCT CAACTGCTGC 701 CTCATCAAGT GGTGCTGTAA AATGCCCAAA CCGGTTAATT CCTTTTCGGT 751 CACCAAGTGC TTGAAGTAAT GCCGTTCCAA TTGCTAAAGC AATATCCTCA 801 TTTGAGTGAT GATCATCAAT GTGTGTGTCA CCCGTCGCCT TCACGTATAC 851 ATCAAACAGT CCATGAGATG CCAGTTGATC AAGCATGTGA TCCAAGAACG 901 GTATCCCTGT GCTGGAGTTT GCAACACCAG TGCCGTCCAG GTTGATCTTG 951 ACATGCACAT TTGTTTCCTT GGTTACCCGc TTGACCTCCC CCCACCCCAC 1001 TTCTCCTTCT ACGTGGAACA ACACCTGCGG AGGGCGCGCC CAGGGAGCAG 1051 CAGGCGCTGC TCGAGCTTGA GGACACCGCC GCGCGGCTGA GACGGGAGCG 1101 GGACACGCTC CGCAACACTC TCAaCTACCT TACCGCCGCG TCTGCCGtCA 1151 AGGACGTCTT CCCCTCGTCG CCGTCGTCGG GGTGAAGCCT TTCGCCTCTG 1201 CCCCATCTCG CTCGCCGATA AGGAGTTTGT GGAGGGTAGT GGACTAAACC 1251 TTCTTATTGC TCTTTTTCGC CTTTTTCCTT TCCTTGTAAT TGCAAGGGTA 1301 GGCTTTATtT CAATGTGGTA GCATTTTAGC GTGTAAAAGT GTACGTATAA 1351 TTCAGGTGTA TTAACTCAAA AGGAAAATGC GGAGCTATGA CGATGATCAA 1401 TGGTAATGAT AAGCATTTTG CTCCAAAAAA AAAAAAAAAA AAACCCT TABLE3A(SEQIDNO:9) 1 AGGGTTTTTT TTTTTTTTT TTTGGAGCAA AATGCTTATC ATTACCATTG 51 ATCATCGTCA TAGCTCCGCA TTTTCCTTTT GAGTTAA AC ACCTGAATTA 101 TACGTACACT TTTACACGCT AAAATGCTAC CACATTGAAA TAAAGCCTAC 151 CCTTGCAATT ACAAGGAAAG GAAAAAGGCG AAAAAGAGCA ATAAGAAGGT 201 TTAGTCCACT ACCCTCCACA AACTCCTTAT CGGCGAGCGA GATGGGGCAG 251 AGGCGAAAGG CTTCACCCCG ACGACGGCGA CGAGGGGAAG ACGTCCTTGA 301 CGGCAGACGC GGCGGTAAGG TAGTTGAGAG TGTTGCGGAG CGTGTCCCGC 351 TCCCGTCTCA GCCGCGCGGC GGTGTCCTCA AGCTCGAGCA GCGCCTGCTG 401 CTCCCTGGGC GCGCCCTCGA GGTGTTGCCC ACGTAGAAGG AGAATGGGGT 451 GGGGGGAGGT CAAGCGGGTA ACCAAGGAAA CAAATGTGCA TGTCAAGATC 501 AACCTGGACG GCACTGGTGT TGCAAACTCC AGCACAGGGA TACCGTTCTT 551 GGATCACATG CTTGATCAAC TGGCATCTCA TGGACTGTTT GATGTATACG 601 TGAAGGCGAC GGGTGACACA CACATTGATG ATCATCACTC AAATGAGGAT 651 ATTGCTTTAG CAATTGGAAC GGCATTACTT CAAGCACTTG GTGACCGAAA 701 AGGAATTAAC CGGTTTGGGC ATTTTACAGC ACCACTTGAT GAGGCAGCAG 751 TTGAGGTTAT ACTGGATCTA TCTGGTCGAC CTCATTTGAG CTGCGGCTTA 801 AGCATTCCTA CCGAAAGAGT TGGCACATAT GACACACAGC TAGTTGAGCA 851 TTTCTTCCAG TCCCTTGTGA ATACATCTGG CATGACGCTT CACATCCGTC 901 AGCTTGCGGG AAACAACTCA CACCATATTA TCGAGGCAAC tTTCAAAGCA 951 TTTGCCAGGG CGCTTCGACA AGCAACGGAA TATGACTTAC GCCGCCAGGG 1001 CACTATGCCA AGCTCAAAAG GTGTTCTGTC AAGGTCTTAG TGTTGCAATG 1051 CAAGATCGAA AACTGGACGC ACGCTATTCG CCCTCAAAGA AACACATGGG 1101 CGGTCGCCTG CTATGTCTCT GCTGCTACTT GGACTTGCAG TCCGCGGGGT 1151 TTGGAACAAG AACAGCATGG AAATTGCTTG TTATCCTGTT GTCAGGGTTT 1201 GTTTATCTTA CTACCATTGG CATACTGTAT CTGCTCGCTA CTGCAGTTTT 1251 GCTGGACAAC ACTTACATCT GAAGATGTAA AAGCTGCAGA CGGCTTGACA 1301 TTCTGAAAGT TATTACCTCT GATATATGGA TTCAGCATTG GTTTGCGCGG 1351 TGTTGCGCCT GTAATAATGG TTTGGCCATT CAAAAGAGTG AAATGAAATA 1401 GAATAATAAT CTCCAAAAAA AAAAAAAAAA AACTCGAGGG GGGG The cDNA sequence shown in Table 3A was cloned into the plasmid pBluescript, resulting in plasmid pWIGPD. This plasmid was deposited on April 26, 1994 with the Agricultural Research Service, Patent Culture Collection (NRRL), Northern Regional Research Center, 1815 North University Street, Peoria, Illinois 61604, U.S.A. and was assigned accession number NRRL B- . This example constitutes an experimental protocol with which those skilled in the art can obtain IGPD cDNAs or genes from any other higher plant species in a relatively straight¬ forward fashion. An alignment of the predicted amino acid sequences of the respective proteins encoded by the sequences shown in Tables 1 (from nucleotide 249 to 831) and 3A (from nucleotide 453 to 1037), is set forth in Table 4. TABLE 4 Arab. 1 .MALGRIGEVKRVTKETNVSVKINLDGTGVADSSSGIPFLDHMLDQLASH 49 I I I I I I I I I I I I I I I I I I I I I I I :l I. I I I I I I I I I I I I I I I wheat 1 GEVKRVTKETNVHVKINLDGTGVANSSTGIPFLDHMLDQLASH 49 50 GLFDVHVRATGDVHIDDHHTNEDIALAIGTALLKALGERKGINRFGDFTA 99 I I I I I . I :| I I I . I I I I I I .1 I I I I I I I I I I I I .1 I I :| I I I I I I I. I I I 50 GLFDVYVKATGDTHIDDHHSNEDIALAIGTALLQALGDRKGINRFGHFTA 99 100 PLDEALIHVSLDLSGRPYLGYNLEIPTQRVGTYDTQLVEHFFQSLVNTSG 149 I I I I I :• I I I I I I I I .!::. I .1 I I :l I I I I I I I I I I I I I I I I ! I I I I 100 PLDEAAVEVILDLSGRPHLSCGLSIPTERVGTYDTQLVEHFFQSLVNTSG 149 150 MTLHIRQLAGENSHHIIEATFKAFARALRQATETDPRRGGTIPSSKGVLS 199 I I I I I I I I I I: I I I I I I I I I I I I I I I i I I I I I I I 11.11:11111111 150 MTLHIRQLAGNNSHHIIEATFKAFARALRQATEYDLRRQGTMPSSKGVLS 199 200 RS 201 I I 200 RS 201 Identical residues are denoted by the vertical bar between the two sequences. Alignment is performed using the GAP program described in Deveraux et al., Nucleic Acids Res. 12:387-395 (1984). Regions corresponding to peptide sequences determined from the purified wheat germ IGPD (see Example 7, below) are underlined. Example 4: Expression of recombinant IGPD in E. coli To produce recombinant higher plant IGPD in E. coli, a translational fusion of the Arabidopsis IGPD cDNA to the 5' end of the lacZ gene was created in pBluescript SK (Stratagene, La Jolla), using the PCR overlap extension technique. Synthetic oligonucleotide primers SV124 (of sequence 5'-TGC AAT CCG CGG GTA GAA TTG GAG AAG TAA-3'; SEQ ID NO: 5) and SV122 (of sequence 5'-TGC TCC ACC AAC TGA GTA TC-3'; SEQ ID NO: 6 were used in a polymerase chain reaction to amplify a DNA fragment of pSTA3 approximately 418 bp in length. The PCR product was digested at its unique SacII and Xbal sites, resulting in a fragment approximately 300 bp in length. The digestion products were separated on a low-gelling-temperature agarose gel, and the 300 bp SacII-Xbal fragment was excised. In parallel, plasmid pSTA3 was digested with SacII and Xbal, the products were separated on a gel, and the large fragment from the digestion, containing the pBluescript vector and 3' portion of the IGPD cDNA, was excised from the gel. This vector fragment was ligated to the 300 bp SacII-Xbal digested PCR product, and the ligation products were transformed into competent E. coli XL1 Blue cells (Stratagene, La Jolla, CA). Ampicillin resistant colonies were selected, cultured, and their plasmid DNAs extracted. The structures of the plasmids were confirmed by sequencing with the dideoxy chain termination method. A recombinant plasmid with the expected structure was designated placIGPD. The resulting fusion protein produced by this strain contained approximately 23 amino acids of the N-terminus of beta-galactosidase, followed by the presumptive mature coding sequence for Arabidopsis IGPD, which begins at codon 73 of the predicted protein coding sequence. Another plasmid for expression of higher plant IGPD in coli was constructed by inserting the presumptive mature coding sequence of IGPD into the vector pFLAG (International Biotechnologies, Inc., New Haven, CT). Example 5: Expression of recombinant IGPD in insect cells via a baculovirus expression system The IGPD cDNA was excised from pSTA3 and ligated into the baculovirus transfer vector pVL1392 (Invitrogen Corp., San Diego, CA). The resulting plasmid contained the Arabidopsis IGPD coding sequence downstream of the polyhedrin promoter. The plasmid was co-transfected into Spodoptera frugiperda cultured cell line Sf21 (Invitrogen Corp., San Diego, CA) which was further transgected with wild-type AcMNPV DNA. Recombinant plaques were identified by the absence of refractile polyhedrin crystals under microscopic examination. A high titer virus stock was prepared from a single recombinant plaque. To produce recombinant IGPD, Sf21 cells (0.8xl0 6 cells/ml) are infected with virus at a Multiplicity of Infection (MOI) of 10. Three days after infection, the crude extract from the infected Sf21 cells was assayed for IGPD activity as described above. The results are summarized in Table 5, below. The specific activity of the extract from the infected Sf21 cells was determined to be 4.7 mu/mg, with a total activity of 1.3 units/liter. Comparison of IGPD expression levels in Table 5 shows that Arabidopsis IGPD expressed in Tn cells gave high IGPD activity in the culture medium. TABLE 5 Comparison of IGPD expression levels Arabidopsis . IGPD (recombinant) Wheat Germ IGPD Host cells Sf21 Tn E. coli*** acetone Powder Starting Material 1 liter culture 500 g Purification Crude Cell Culture (NH4)2SO4 precipitate Step Homogenate Medium Total activity 1.3 4.0 0.031 1.5 (units) Specific Activity 4.7* 6.5** 0.28 0.10 (m unit/mg protein) * denotes specific activity in the cell homogenate, since the expressed protein accumulated in Sf21 cells; ** denotes specific activity in the culture medium (without serum), since the expressed protein was secreted to the culture medium; and *** denotes E. coli expressing pSTA3. Example 6: Expression of the Arabidopsis IGPD cDNA in transgenic plants To express the Arabidopsis protein in transgenic plants, the full length cDNA contained in pSTA3 was inserted into the plant expression vector pCGN1761ENX, which was derived from pCGN1761 (EP-392 225) as follows. pCGN1761 was digested at its unique EcoRI site, and ligated to a double-stranded DNA fragment comprised of two oligonucleotides of sequence 5'- AAT TAT GAC GTA ACG TAG GAA TTAGCG GCCC GCT CTC GAG T-3' (SEQ ID NO: 7) and 5'-AAT TAC TCG AGA GCG GCC GCG AAT TCC TAC GTT ACG TCA T-3' (SEQ ID NO: 8). The resulting plasmid, pCGN1761ENX, contained unique EcoRI, NotI, and Xhol sites that lie between a duplicated 35S promoter from cauliflower mosaic virus (Kay et al., Science 236:1299-1302 (1987)) and the 3' untranslated sequences of the tml gene of Agrobacterium tumefaciens. This plasmid was digested with EcoRI and Xhol, and ligated to an EcoRI/XhoI fragment resulting from partial digestion of pSTA3, such that it carried the complete IGPD cDNA. (The cDNA contained an internal EcoRI site). From this plasmid was excised an Xbal fragment comprising the Arabidopsis IGPD cDNA flanked by a duplicated 35S promoter and the 3' untranslated sequences of the tml gene of A^ tumefaciens. This Xbal fragment was inserted into the binary vector pCIB200 (EP-332 104) at its unique Xbal site, which lies between T-DNA border sequences. The resulting plasmid, designated pCIB200IGPD, was transformed into A tumefaciens strain CIB542. See, Uknes et al., Plant Cell 5:159-169 (1993). Leaf disks of Nicotiana tabacum cv. Xanthi-nc were infected with A^ tumefaciens CIB542 harboring pCIB200IGPD as described by Horsch et al, Science 227: 1229 (1985). Kanamycin-resistant shoots from 15 independent leaf disks were transferred to rooting medium, then transplanted to soil and the resulting plants grown to maturity in the greenhouse. Seed from these plants were collected and germinated on MS agar medium containing kanamycin. Ten individual kanamycin resistant seedlings from each independent primary transformant were grown to maturity in the greenhouse, and their seed collected. These seeds were germinated on MS agar medium containing kanamycin. Plant lines that gave rise to exclusively kanamycin resistant seedlings were homozygous for the inserted gene and were subjected to further analysis. Leaf disks of each of the 15 independent transgenic lines were excised with a paper punch and placed onto MS agar containing 0 or 30 ppm of a specific IGPD inhibitor represented by formula (IV), namely: After three weeks, two sets of 10 disks from each line were weighed, and the results recorded. Transgenic lines designated IGPD-C, E, and G were approximately 3-fold more resistant to or tolerant of the inhibitor than wild type, non-transformed plants. RNA was extracted from leaves of each of these lines. Total RNA from each independent homozygous line, and from non-transgenic control plants, was separated by agarose gel electrophoresis in the presence of formaldehyde (Ausubel et al., Current Protocols in Molecular Biology, Wiley & Sons, New York (1987)). The gel was blotted to nylon membrane (Ausubel et al., supra.) and hybridized with the radiolabelled Arabidopsis IGPD cDNA. Hybridization and washing conditions were as described by Church and Gilbert, Proc. Natl. Acad. Sci. USA 81:1991-1995 (1984). The filter was autoradiographed, and intense RNA bands corresponding to the IGPD transgene were detected in all four transgenic plant lines. Seeds of the IGPD-G line displaying the highest apparent level of Arabidopsis IGPD message were tested for resistance to or tolerance of the specific IGPD inhibitor represented by formula (I). Seeds from the transgenic line and from wild type non-transformed tobacco were germinated on MS agar medium containing the inhibitor at concentrations of 1500 and 3000 ppm. Growth of the seedlings was visually scored after two weeks. The results are set forth below in Table 6. TABLE 6 ppm 0 1500 3000 Xanthi +++ + + IGPD-G (IGPD over expresser) +++ +++ ++ + denotes severe inhibition of growth phenotype ++ denotes slight inhibition of growth phenotype +++ denotes no inhibition of growth phenotype The table summarizes visually obtained data concerning seedling growth on the IGPD inhibitor of formula (I). Seedlings of line IGPD-G showed uninhibited growth when germinated on MS medium containing 1,500 ppm IGPD inhibitor of formula (I). At 3,000 ppm, there was only slight inhibition of growth. Wild-type tobacco plants were inhibited on medium containing 1,500 and 3,000 ppm inhibitor of formula (I). Leaves from these homozygous transgenic plants were collected, frozen in liquid nitrogen, and homogenized in 200 mM triethanolamine-HCl, 10% Polyclar AT (WAKO Pure Chemical Co., Osaka, Japan). The extract was filtered through Miracloth (Calbiochem, San Diego, CA), and assayed for IGPD activity as described in Example 7. The activity was determined to be 0.68 mu/mg protein, or 7.45 mu/g fresh weight. This compared favorably to the undetectable level of activity in non- transgenic control tobacco plants, either in a crude extract, or a 30-60% ammonium sulfate fraction. IGPD activities in other plant species are summarized in Table 7. TABLE 7 Specific Extractable Activity Activity Plant Source (mU/mg a ) (mU/g)* Tobacco leaves 0 0 Transgenic tobacco leaves (IGPD-G) 0.68 7.45 Barley shoots (Hordeum vulgare LJ 0.25 0.95 Cabbage shoots (Brassica oleracea L.) 0.13 0.22 Cucumber shoots (Cucumis sativus L.) 0 0 Lettuce shoots (Lactuca sativa L.) 0 0 Maize shoots (Zea mays __) 0.06 0.27 Oats shoots (A vena sativa LJ 0 0 Pea shoots (Pisum sativum ]_____) 0.09 0.61 Rice germ 0.03 0.73 Wheat germ 0.05 3.20 Rose cell culture (Rosa "Paul's" Scarlet) 0.23 0.04 j* Units of acitvity per milligram of protein. " Units of activity per gram of plant material These results indicate that the activity of IGPD in the crude extract of transgenic tobacco plants exceeds the activity of IGPD in the 80% ammonium sulfate fraction from any plant species tested. To further evaluate resistance of the IGPD-overexpressing line IGPD-G, plants were grown in the greenhouse and treated with various concentrations of the IGPD inhibitor represented by formula (IV) above. After treatment plants were photographed, and their health was visually scored. The results are recorded in Table 8, below. TABLE 8 Visual Score after Treatment inhibitor (ppm) Xanthi (untransformed) IGPD-G 0 5 5 1000 3 4 10000 1 2 1 = severe stunting, severe chlorosis combined with necrosis 2 = severe Stunting, some interveinal chlorosis 3 = moderate stunting, some interveinal chlorosis, pinnate leaves 4 = moderate sunting, normal leafe morphology 5 = healthy, with no symptoms Example 7: Purification of IGPD from wheat germ Wheat germ (Sigma Chemical Co., St. Louis) was processed into an acetone powder. The following steps were carried out at 4°C. The acetone powder was suspended in 200 mM triethanolamine-HCl (TEA-HCl) and the insoluble material removed from the filtrate by centrifugation. The supernatant was precipitated with ammonium sulfate (30% saturation) and centrifuged. The supernatant was loaded onto a Butyl-Toyopearl 650M column (TOSOH, Tokyo) equilibrated with 50mM TEA-HCl (pH 7.5) containing 1 mM MgCl2, 100 mM 2-mercaptoethanol, and ammonium sulfate (20% saturation). Enzyme activity was eluted with a linear gradient of ammonium sulfate (20-0% saturation) in the same buffer. Protein was collected by precipitation with ammonium sulfate (80% saturation) and dissolved in 20 mM TEA-HCl (pH 7.5) containing 1 mM MnCl2 and 100 mM 2-mercaptoethanol (purification buffer). After desalting on Sephadex G-25, the extract was loaded onto a DEAE-Toyopearl 650 M column (TOSOH, Tokyo) equilibrated with purification buffer. The enzyme was eluted with a linear gradient of NaCl (0-500 mM) in purification buffer. The active fractions were desalted on Sephadex G-25 and subjected to MonoQ FPLC (Pharmacia-LKB) using purification buffer. The active fractions were pooled and concentrated by ultrafiltration (Amicon YM30). This preparation was chromatographed twice on Superdex 200 FPLC (Pharmacia-LKB) using purification buffer containing 150 mM NaCl. The obtained enzyme preparation was stored at -80°C until used. Table 9 summarizes the purification of IGPD from wheat germ leading to a 114,000-fold purification of the enzyme. TABLE 9 Purification of IGPD from wheat germ Purification Total Total Reco- Specific Purifi¬ step protein activity very activity cation (mg) (mU) (%) (mU/mg) (fold) (NH4) 2 SO 4 fractionation 128,000 6,400 100 0.05 1 Butyl-Toyo¬ pearl hydro- phobic chroma¬ tography 5,600 4,870 76 0.87 17 DEAE-Toyopearl- ionexchange chromatography 565 1,040 16 1.8 36 MonoQ FPLC 25.3 652 10 25.8 516 Superdex 200 FPLC (run twice) 0.035 199 3 5700 114,000 Determination of IGPD activity IGPD activity was determined by measuring imidazoleacetol obtained by hydrolyzing IAP. The dehydratase reaction mixture contained 50 mM Bis-Tris-propane-HCl buffer (pH 6.6), 100 mM 2-mercaptoethanol, 1 mM MnCl2, 1 mN IGP, and 2 to 5 mU of enzyme in a volume of 0.25 ml. The reaction was started by the addition of substrate, incubated at 30°C and stopped after 40 minutes by adding 10% (v/v) of 1 N perchloric acid. After centrifugation, the supernatant was adjusted to pH 10 by 1 M 2-ethylaminoethanol. Alkaline phosphatase and MgCl2 were added to the mixture to reach a final concentration of 25 U/ml and 2.2 mM, respectively. After incubation at 45°C for 20 min, the reaction mixture was chilled in salt-ice. Five volumes of 5 N NaOH were added to the solution, and after 2 minutes, the concentration of enolized imidazoleacetol was determined from the absorbance at 370 nm using the absorbance coefficient of 10,400 (Ames and Mitchell, J. Biol. Chem. 212: 687-697, 1955). One unit of enzyme activity was defined as the amount of enzyme catalyzing the formation of 1 μmol of IAP/imidazoleacetol per minute under the assay conditions. Determination of histidinol phosphatase activity Histidinol phosphatase activity was determined by measuring the formation of inorganic phosphate according to the method described earlier (Ames et al. 1955) with some modifications. The assay mixture contained 200 mM TEA-HCl (pH 8.2), 5 mM L-histidinol phosphate, and enzyme in a final volume of 180 μL. The reaction was started with the addition of substrate, incubated at 37°C for 180 minutes and stopped with 10% (v/v) of 1 N perchloric acid. The mixture was centrifugated at 10,000 rpm for 3 min. An aliquot of 180 μL of the supernatant was mixed with 420 μL of the ascorbate-molybdate reagent and incubated at 45°C for 20 min. The absorption was read at 820 nm against a control without substrate or enzyme. One unit of enzyme activity was defined as the amount of enzyme catalyzing the formation of 1 μmol of phosphate per minute under the assay conditions. Protein determination The protein concentration was determined by the Bradford protein assay method using bovine serum albumin as a standard (Bradford, Anales of Biochemistry 72:248-254, 1976). Electrophoresis SDS-PAGE was carried out according to Laemmli (Nature 227:680-685, 1970) using a gradient gel (Phastgel 8-25, Pharmacia-LKB). Native PAGE was done as described (Davis, Ann. NY Acad. Sci. 121:404-427, 1964) using a slab gradient gel (PAG plate 4/15, Dai-ichi Chemicals, Japan). Isoelectric focusing was carried out using a polyacrylamide gel (4%) with Selvalyt pH 3-7 as the carrier ampholyte. The pi value was calculated using a calibration kit (Pharmacia-LKB). The purified IGPD so obtained was digested with lysyl endopeptidase, and the resulting digest was separated by reverse phase HPLC. The resulting peptides were subjected to automated Edman degradation (Strickler et al., Anal. Biochem. MO: 553-566 (1984)) with an Applied Blosystems (Foster City, CA) 470A protein sequencer. The following peptide sequences were determined: Peptide #1: GINRFGHFTAPLDEA (SEQ ID NO: 10) Peptide #2: GVLSRV (SEQ ID NO: 11) Peptide #1 exactly matched the predicted protein sequence determined from the wheat IGPD cDNA (Table 4, underlined). Peptide # 2 differed from the predicted protein sequence derived from the cDNA at the last residue. The discrepancy compared to the amino acid sequence of the peptide was likely due to the presence of multiple isoforms encoded by different genes in the wheat genome, especially given the fact that Arabidopsis has two IGPD genes as determined by genomic Southern blot. Wheat, with its hexaploid genome, may have even more than two IGPD genes. Furthermore, these sequences were nearly identical to two segments of the predicted protein sequence encoded by the Arabidopsis IGPD cDNA (Table 4). All publications and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. Various modifications of the invention described herein will become apparent to those skilled in the art. Such modifications are intended to fall within the scope of the appended claims. DEPOSIT Plasmid pSTA3: ATCC 75014 REFERENCES CITED Ames and Mitchell, J. Biol. Chem. 212: 687-697, 1955 Ames, J. Biol. Chem. 228:131-143, 1957 Ausubel et al., Current Protocols in Molecular Biology, Wiley & Sons, New York (1987) Boutry et al., Nature 328:340-342, 1987 Bradford, Anales of Biochemistry 72:248-254, 1976 Chang et al. Proc. Natl. Acad, Sci, USA 85:6856-6860, 1988 Chrispeels, Ann. Rev. Plant Physiol. Plant Mol. Biol. 42: 21-53, 1991 Christou et al., Plant Physiol. 87:671-674, 1988 Church and Gilbert, Proc. Natl. Acad. Sci. USA 81:1991-1995, 1984 Crossway et al., BioTechniques 4:320-334, 1986 Davis et al., Advanced Bacterial Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1980 Datta et al, Bio/Technology 8:736-740, 1990 Davis, Ann. NY Acad. Sci. 121:404-427, 1964 Delauney et al., Mol. Genet. 221:299-305, 1990 Deveraux et al., Nucleic Acids Res. 12:387-395, 1984 Elledge et al, Proc. Natl. Acad. Sci, USA 88:1731-1735, 1991 Eller et al., Plant Mol. Biol. 18:557-566, 1992 Frisch et al., Mol. Gen. Genet. 228:287-293, 1991 Fromm et al., Bio Technology 8:833-839, 1990 Gordon-Kamm et al., Plant Cell 2:603-618, 1990 Heijne et al., Plant Mol. Biol. Rep. 9:104-126, 1991 Hilton et al., Arch. Biochem. Biophys. 112:544-547, 1965 Hinchee et al., Biotechnology 6:915-921, 1988 Horsch et al, Science 227: 1229, 1985 Hudspeth et al, Plant Mol Biol 12:579-589, 1989 Hutchinson et al., Proc. Natl. Acad. Sci. USA, 83:710-714, 1986 Jeim and Larrinua, Plant Physiol. 91:1226-1231, 1989 Kadonaga et al., Nucleic Acids Res. 13:1733-1745, 1985 Kay et al., Science 236: 1299-1302, 1987 Klein al., Proc. Natl. Acad. Sci. USA, 85:4305-4309, 1988 Klein et al., Bio/Technology 6:559-563, 1988 Klein et al., Plant Physiol. 91:440-444, 1988 Laemmli, Nature 227:680-685, 1970 Leung et al., Technique 1:11-15, 1989 Luckow and Summers, Bio/Technology 6:47-55, 1988 McCabe et al., Biotechnology 6:923-926, 1988 Miller, Experiments in Molecular Genetics. Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1972 Minet et al., Plant J. 2:417-422, 1992 Morelli et al, Nature 315:200-204, 1985 Nagai et al., Proc. Natl. Acad. Sci USA 88, 4133, 1991 Nam et al., Plant Cell 1:699-705, 1989 Neuhaus et al., Proc. Natl. Acad. Sci. USA 88: 10362-10366, 1991 Paszkowski et al, EMBO J. 3:2717-2722, 1984 Payne et al., Plant Mol. Biol. H:89-94, 1988 Riggs et al, Proc. Natl. Acad. Sci. USA 83:5602-5606, 1986 Sanford et al., Particulate Science and Technology 5:27-37, 1987 Scopes, Protein Purification: Principles and Practice, 2nd Ed., Springer- Verlag, New York, 1987 Sherman et al., Methods in Yeast Genetics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1983 Shiraishi et al., Gene 64:313-319, 1988 Shortle et al., Proc. Natl. Acad. Sci. USA, 79:1588-1592, 1982 Shortle et al., Methods Enzy ol. 100:457-468, 1983 Snustad et al, Genetics 120:111 1-1 1 14, 1988 Strickler et al., Anal. Biochem. HO: 553-566, 1984 Svab et al. Proc. Natl. Acad. Sci. USA 87:8526-8530, 1990 Uknes et al., Plant Cell 5:159-169, 1993 Vogel and Bonner, J. Biol. Chem. 218:97-106, 1956 Weissinger et al, Annual Rev. Genet. 22:421-477, 1988 EP-332 104 EP-392 225 EP-462065 US-4,945,050 SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: (A) NAME: CIBA-GEIGY AG (B) STREET: Klybec strasse 141 (C) CITY: Basel (D) COUNTRY: Switzerland (E) POSTAL CODE (ZIP) : 4002 (ii) TITLE OF INVENTION: Herbicide Resistant Plants (iii) NUMBER OF SEQUENCES: 12 (iv) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentln Release #1.0, Version #1.25 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1140 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Arabidopsis thaliana (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 1..1140 (C) IDENTIFICATION METHOD: experimental (D) OTHER INFORMATION: /evidence= EXPERIMENTAL /note= "Arabidopsis cDNA encoding IGPD contained in pSTA3" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: GTTCCTTCCG CTGCCAACAA AATGGAGCTG TCGTCTGCGT CCGCCATATT AAGCCACTCC 60 TCCTCCGCCG CTCAGCTTCT CAGACCTAAG CTCGGGTTTA TTGATTTGCT TCCTCGTCGA 120 GCGATGATCG TTTCTTCTCC TTCTTCTTCG CTTCCTCGAT TTTTGCGGAT GGAATCTCAA 180 TCTCAGCTTC GCCAATCTAT CTCTTGCTCT GCTTCTTCTT CTTCTTCTAT GGCATTAGGT 240 AGAATTGGAG AAGTAAAGAG AGTAACAAAG GAAACGAATG TTTCAGTGAA GATTAATTTG 300 GATGGTACTG GAGTTGCAGA TAGTTCTAGT GGAATTCCTT TCCTTGACCA TATGTTAGAT 360 CAACTTGCTT CGCATGGCTT GTTTGATGTG CACGTTAGAG CTACTGGTGA TGTTCACATT 420 GATGATCATC ACACTAATGA AGATATAGCT CTTGCCATTG GAACTGCTCT ATTAAAGGCT 480 CTTGGTGAGC GTAAAGGGAT TAACCGGTTT GGTGACTTCA CAGCTCCTCT AGATGAAGCG 540 CTTATACATG TTTCCTTGGA CTTGTCTGGT CGACCATATC TTGGTTACAA CTTGGAGATA 600 CCAACTCAGA GAGTTGGAAC ATATGATACT CAGTTGGTGG AGCACTTTTT CCAGTCGTTG 660 GTGAATACTT CTGGTATGAC TCTTCACATT CGGCAGCTCG CTGGTGAAAA CTCTCATCAC 720 ATAATAGAGG CGACGTTTAA GGCGTTTGCC AGAGCTCTAC GACAAGCAAC AGAGACTGAT 780 CCACGCCGTG GTGGGACAAT ACCAAGTTCA AAAGGAGTCT TATCACGGTC TTGAAAGCTA 840 ATCAAACACA CAAGACAGTT CCCAGATTCA CACTTCATCG TCGAGTTCAT GAGCCATCGT 900 CAATTCTCTT ATGGTACCAA ATGCCAAGCC TGTTGGATCT TGCTGTTCCA TTCCATTACA 960 GAAGCACAAA GAGCAAAATG TGAAAATAGA TTAGAGATCA CACAGTTCAG AAGATCATAG 1020 GCTCATCTTT ATATTAATCT GTTGTTGCAG AGTGTATTAA ACCTCTTACC ATTGCTGTAT 1080 CATCATCAAC TGAGAACTTA CTGTGAGTTG AAGTGACTGT AATTTGCTTT AAAAAAAAAA 1140 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1447 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: YES (vi) ORIGINAL SOURCE: (A) ORGANISM: Triticum aestivum (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 1..1447 (C) IDENTIFICATION METHOD: experimental (D) OTHER INFORMATION: /evidence= EXPERIMENTAL /note= "full length cDNA clone of IGPD from wheat" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: CCCCCCCTCG AGTTTTTTTT TTTTTTTTT GGAGATTATT ATTCTATTTC ATTTCACTCT 60 TTTGAATGGC CAAACCATTA TTACAGGCGC AACACCGCGC AAACCAATGC TGAATCCATA 120 TATCAGAGGT AATAACTTTC AGAATGTCAA GCCGTCTGCA GCTTTTACAT CTTCAGATGT 180 AAGTGTTGTC CAGCAAAACT GCAGTAGCGA GCAGATACAG TATGCCAATG GTAGTAAGAT 2 0 AAACAAACCC TGACAACAGG ATAACAAGCA ATTTCCATGC TGTTCTTGTT CCAAACCCCG 300 CGGACTGCAA GTCCAAGTAG CAGCAGAGAC ATAGCAGGCG ACCGCCCATG TGTTTCTTTG 360 AGGGCGAATA GCGTGCGTCC AGTTTTCGAT CTTGCATTGC AACACTAAGA CCTTGACAGA 420 ACACCTTTTG AGCTTGGCAT AGTGCCCTGG CGGCGTAAGT CATATTCCGT TGCTTGTCGA 480 AGCGCCCTGG CAAATGCTTT GAAGTTGCCT CGATAATATG GTGTGAGTTG TTTCCCGCAA 540 GCTGACGGAT GTGAAGCGTC ATGCCAGATG TATTCACAAG GGACTGGAAG AAATGCTCAA 600 CTAGCTGTGT GTCATATGTG CCAACTCTTT CGGTAGGAAT GCTTAAGCCG CAGCTCAAAT 660 GAGGTCGACC AGATAGATCC AGTATAACCT CAACTGCTGC CTCATCAAGT GGTGCTGTAA 720 AATGCCCAAA CCGGTTAATT CCTTTTCGGT CACCAAGTGC TTGAAGTAAT GCCGTTCCAA 780 TTGCTAAAGC AATATCCTCA TTTGAGTGAT GATCATCAAT GTGTGTGTCA CCCGTCGCCT 840 TCACGTATAC ATCAAACAGT CCATGAGATG CCAGTTGATC AAGCATGTGA TCCAAGAACG 900 GTATCCCTGT GCTGGAGTTT GCAACACCAG TGCCGTCCAG GTTGATCTTG ACATGCACAT 960 TTGTTTCCTT GGTTACCCGC TTGACCTCCC CCCACCCCAC TTCTCCTTCT ACGTGGAACA 1020 ACACCTGCGG AGGGCGCGCC CAGGGAGCAG CAGGCGCTGC TCGAGCTTGA GGACACCGCC 1080 GCGCGGCTGA GACGGGAGCG GGACACGCTC CGCAACACTC TCAACTACCT TACCGCCGCG 1140 TCTGCCGTCA AGGACGTCTT CCCCTCGTCG CCGTCGTCGG GGTGAAGCCT TTCGCCTCTG 1200 CCCCATCTCG CTCGCCGATA AGGAGTTTGT GGAGGGTAGT GGACTAAACC TTCTTATTGC 1260 TCTTTTTCGC CTTTTTCCTT TCCTTGTAAT TGCAAGGGTA GGCTTTATTT CAATGTGGTA 1320 GCATTTTAGC GTGTAAAAGT GTACGTATAA TTCAGGTGTA TTAACTCAAA AGGAAAATGC 1380 GGAGCTATGA CGATGATCAA TGGTAATGAT AAGCATTTTG CTCCAAAAAA AAAAAAAAAA 1440 AAACCCT 1447 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 201 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: YES (iv) ANTI-SENSE: NO (ix) FEATURE : (A) NAME/KEY: Protein (B) LOCATION: 1..201 (D) OTHER INFORMATION: /note= "predicted amino acid sequence of IGPD derived from SEQ ID NO:l" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: Met Ala Leu Gly Arg lie Gly Glu Val Lys Arg Val Thr Lys Glu Thr 1 5 10 15 Asn Val Ser Val Lys lie Asn Leu Asp Gly Thr Gly Val Ala Asp Ser 20 25 30 Ser Ser Gly lie Pro Phe Leu Asp His Met Leu Asp Gin Leu Ala Ser 35 40 45 His Gly Leu Phe Asp Val His Val Arg Ala Thr Gly Asp Val His lie 50 55 60 Asp Asp His His Thr Asn Glu Asp lie Ala Leu Ala lie Gly Thr Ala 65 70 75 80 Leu Leu Lys Ala Leu Gly Glu Arg Lys Gly lie Asn Arg Phe Gly Asp 85 90 95 Phe Thr Ala Pro Leu Asp Glu Ala Leu lie His Val Ser Leu Asp Leu 100 105 110 Ser Gly Arg Pro Tyr Leu Gly Tyr Asn Leu Glu lie Pro Thr Gin Arg 115 120 125 Val Gly Thr Tyr Asp Thr Gin Leu Val Glu His Phe Phe Gin Ser Leu 130 135 140 Val Asn Thr Ser Gly Met Thr Leu His lie Arg Gin Leu Ala Gly Glu 145 150 155 160 Asn Ser His His lie lie Glu Ala Thr Phe Lys Ala Phe Ala Arg Ala 165 170 175 Leu Arg Gin Ala Thr Glu Thr Asp Pro Arg Arg Gly Gly Thr lie Pro 180 185 190 Ser Ser Lys Gly Val Leu Ser Arg Ser 195 200 (2) INFORMATION FOR SEQ ID NO:4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 195 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: YES (iv) ANTI-SENSE: NO (ix) FEATURE : (A) NAME/KEY: Protein (B) LOCATION: 1..195 (D) OTHER INFORMATION: /note= "predicted amino acid sequence derived from SEQ ID NO:9" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4: Gly Glu Val Lys Arg Val Thr Lys Glu Thr Asn Val His Val Lys He 1 5 10 15 Asn Leu Asp Gly Thr Gly Val Ala Asn Ser Ser Thr Gly He Pro Phe 20 25 30 Leu Asp His Met Leu Asp Gin Leu Ala Ser His Gly Leu Phe Asp Val 35 40 45 Tyr Val Lys Ala Thr Gly Asp Thr His He Asp Asp His His Ser Asn 50 55 60 Glu Asp He Ala Leu Ala He Gly Thr Ala Leu Leu Gin Ala Leu Gly 65 70 75 80 Asp Arg Lys Gly He Asn Arg Phe Gly His Phe Thr Ala Pro Leu Asp 85 90 95 Glu Ala Ala Val Glu Val He Leu Asp Leu Ser Gly Arg Pro His Leu 100 105 110 Ser Cys Gly Leu Ser He Pro Thr Glu Arg Val Gly Thr Tyr Asp Thr 115 120 125 Gin Leu Val Glu His Phe Phe Gin Ser Leu Val Asn Thr Ser Gly Met 130 135 140 Thr Leu His He Arg Gin Leu Ala Gly Asn Asn Ser His His He He 145 150 155 160 Glu Ala Thr Phe Lys Ala Phe Ala Arg Ala Leu Arg Gin Ala Thr Glu 165 170 175 Tyr Asp Leu Arg Arg Gin Gly Thr Met Pro Ser Ser Lys Gly Val Leu 180 185 190 Ser Arg Ser 195 (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: Other nucleic acid (A) DESCRIPTION: PCR primer SV124 used to aπplify fragment from pSTA3 (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5: TGCAATCCGC GGGTAGAATT GGAGAAGTAA 30 (2) INFORMATION FOR SEQ ID NO:6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 20 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: Other nucleic acid (A) DESCRIPTION: PCR primer SV122 used to amplify fragment from pSTA3 (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6: TGCTCCACCA ACTGAGTATC 20 (2) INFORMATION FOR SEQ ID NO:7: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 41 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: Other nucleic acid (A) DESCRIPTION: Oligonucleotide used to create pCGN1761ENX (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7: AATTATGACG TAACGTAGGA ATTAGCGGCC CGCTCTCGAG T 41 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 40 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: Other nucleic acid (A) DESCRIPTION: Oligonucleotide used to create pCGN1761ENX (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8: AATTACTCGA GAGCGGCCGC GAATTCCTAC GTTACGTCAT 40 (2) INFORMATION FOR SEQ ID NO:9: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1444 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 1..1444 (D) OTHER INFORMATION: /note= "apparent full length cDNA clone of wheat IGPD; protein sequence in SEQ ID NO: " (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 453..1037 (D) OTHER INFORMATION: /product---- "mature IGPD from wheat" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9: AGGGTTTTTT TTTTTTTTTT TTTGGAGCAA AATGCTTATC ATTACCATTG ATCATCGTCA 60 TAGCTCCGCA TTTTCCTTTT GAGTTAATAC ACCTGAATTA TACGTACACT TTTACACGCT 120 AAAATGCTAC CACATTGAAA TAAAGCCTAC CCTTGCAATT ACAAGGAAAG GAAAAAGGCG 180 AAAAAGAGCA ATAAGAAGGT TTAGTCCACT ACCCTCCACA AACTCCTTAT CGGCGAGCGA 240 GATGGGGCAG AGGCGAAAGG CTTCACCCCG ACGACGGCGA CGAGGGGAAG ACGTCCTTGA 300 CGGCAGACGC GGCGGTAAGG TAGTTGAGAG TGTTGCGGAG CGTGTCCCGC TCCCGTCTCA 360 GCCGCGCGGC GGTGTCCTCA AGCTCGAGCA GCGCCTGCTG CTCCCTGGGC GCGCCCTCGA 420 GGTGTTGCCC ACGTAGAAGG AGAATGGGGT GG GGG GAG GTC AAG CGG GTA ACC 473 Gly Glu Val Lys Arg Val Thr 1 5 AAG GAA ACA AAT GTG CAT GTC AAG ATC AAC CTG GAC GGC ACT GGT GTT 521 Lys Glu Thr Asn Val His Val Lys He Asn Leu Asp Gly Thr Gly Val 10 15 20 GCA AAC TCC AGC ACA GGG ATA CCG TTC TTG GAT CAC ATG CTT GAT CAA 569 Ala Asn Ser Ser Thr Gly He Pro Phe Leu Asp His Met Leu Asp Gin 25 30 35 CTG GCA TCT CAT GGA CTG TTT GAT GTA TAC GTG AAG GCG ACG GGT GAC 617 Leu Ala Ser His Gly Leu Phe Asp Val Tyr Val Lys Ala Thr Gly Asp 40 45 50 55 ACA CAC ATT GAT GAT CAT CAC TCA AAT GAG GAT ATT GCT TTA GCA ATT 665 Thr His He Asp Asp His His Ser Asn Glu Asp He Ala Leu Ala He 60 65 70 GGA ACG GCA TTA CTT CAA GCA CTT GGT GAC CGA AAA GGA ATT AAC CGG 713 Gly Thr Ala Leu Leu Gin Ala Leu Gly Asp Arg Lys Gly He Asn Arg 75 80 85 TTT GGG CAT TTT ACA GCA CCA CTT GAT GAG GCA GCA GTT GAG GTT ATA 761 Phe Gly His Phe Thr Ala Pro Leu Asp Glu Ala Ala Val Glu Val He 90 95 100 CTG GAT CTA TCT GGT CGA CCT CAT TTG AGC TGC GGC TTA AGC ATT CCT 809 Leu Asp Leu Ser Gly Arg Pro His Leu Ser Cys Gly Leu Ser He Pro 105 110 115 ACC GAA AGA GTT GGC ACA TAT GAC ACA CAG CTA GTT GAG CAT TTC TTC 857 Thr Glu Arg Val Gly Thr Tyr Asp Thr Gin Leu Val Glu His Phe Phe 120 125 130 135 CAG TCC CTT GTG AAT ACA TCT GGC ATG ACG CTT CAC ATC CGT CAG CTT 905 Gin Ser Leu Val Asn Thr Ser Gly Met Thr Leu His He Arg Gin Leu 140 145 150 GCG GGA AAC AAC TCA CAC CAT ATT ATC GAG GCA ACT TTC AAA GCA TTT 953 Ala Gly Asn Asn Ser His His He He Glu Ala Thr Phe Lys Ala Phe 155 160 165 GCC AGG GCG CTT CGA CAA GCA ACG GAA TAT GAC TTA CGC CGC CAG GGC 1001 Ala Arg Ala Leu Arg Gin Ala Thr Glu Tyr Asp Leu Arg Arg Gin Gly 170 175 180 ACT ATG CCA AGC TCA AAA GGT GTT CTG TCA AGG TCT TAGTGTTGCA 1047 Thr Met Pro Ser Ser Lys Gly Val Leu Ser Arg Ser 185 190 195 ATGCAAGATC GAAAACTGGA CGCACGCTAT TCGCCCTCAA AGAAACACAT GGGCGGTCGC 1107 CTGCTATGTC TCTGCTGCTA CTTGGACTTG CAGTCCGCGG GGTTTGGAAC AAGAACAGCA 1167 TGGAAATTGC TTGTTATCCT GTTGTCAGGG TTTGTTTATC TTACTACCAT TGGCATACTG 1227 TATCTGCTCG CTACTGCAGT TTTGCTGGAC AACACTTACA TCTGAAGATG TAAAAGCTGC 1287 AGACGGCTTG ACATTCTGAA AGTTATTACC TCTGATATAT GGATTCAGCA TTGGTTTGCG 1347 CGGTGTTGCG CCTGTAATAA TGGTTTGGCC ATTCAAAAGA GTGAAATGAA ATAGAATAAT 1407 AATCTCCAAA AAAAAAAAAA AAAAACTCGA GGGGGGG 1444 (2) INFORMATION FOR SEQ ID NO:10: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 15 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: peptide (iii) HYPOTHETICAL: NO (v) FRAGMENT TYPE: internal (ix) FEATURE: (A) NAME/KEY: Peptide (B) LOCATION: 1..15 (D) OTHER INFORMATION: /note= "Sequence for internal peptide #1 of purified IGPD" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10: Gly He Asn Arg Phe Gly His Phe Thr Ala Pro Leu Asp Glu Ala 1 5 10 15 (2) INFORMATION FOR SEQ ID NO:11: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 6 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: peptide (iii) HYPOTHETICAL: NO (v) FRAGMENT TYPE: internal (ix) FEATURE: (A) NAME/KEY: Peptide (B) LOCATION: 1..6 (D) OTHER INFORMATION: /note= "Sequence for internal peptide #2 of purified IGPD" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11: Gly Val Leu Ser Arg Val 1 5 (2) INFORMATION FOR SEQ ID NO:12: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 787 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Arabidopsis thaliana (vii) IMMEDIATE SOURCE: (B) CLONE: pIGPDat.2 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12: GGCACGAGGA TCAACTTGCT TCACATGGCT TGTTCGATGT ACACGTAAGA GCTACTGGTG 60 ATACTCACAT TGATGATCAT CATACTAATG AAGATGTTGC TCTTGCCATT GGAACTGCTT 120 TGTTAAAGGC ACTTGGGGAA CGGAAAGGGA TTAATCGTTT TGGCGATTTT ACAGCTCCTC 180 TTGATGAAGC ACTCATACAT GTTTCCCTGG ATCTATCTGG TAGACCATAT CTTGGATACA 240 ACTTAGAGAT TCCAACGCAG AGAGTAGGAA CATACGACAC TCAGTTGGTG GAACACTTCT 300 TCCAGTCATT GGTGAATACT TCTGGTATGA CTCTTCACAT CCGACAGCTT GCTGGTAAAA 360 ACTCGCATCA CATAATAGAA GCGACCTTTA AGGCCTTTGC AAGAGCTCTC CGACAAGCAA 420 CAGAGTCTGA TCCACGCCGC GGTGGGACAA TACCAAGCTC GAAAGGAGTC TTGTCACGTT 480 CATAAGAGGA CTTGATGAGC ATGGGTCAGT TGTCTGAATG TCTTATGTAC AATGTCAAAC 540 ATGCTGGATC TTTGTTCATT TGCAAAGGTC AATGTATCTA ATCTAGCTAA TTGATTATTG 600 TTGGTCACCA GGATCTTTTT GCTCTCTCTA GTTCTAGACT TTGTTCACCT TAAGCCAGAG 660 CTCTTTAATC AGGAGTTACT CGTAATCATT TTGTTTTGGT CATGTGTGCA CCATTTACGA 720 GTGTCATGCT CGTGATTCAT GGAGCTTTAC TCTGTATTGT TTGTCCAAAA AAAAAAAAAA 780 AAAAAAA 787

Claims: WE CLAIM; 1. A plant, plant tissue or plant seed, wherein the growth and development of said plant is tolerant of inhibition by an imidazole or triazole herbicide, or mixtures thereof, wherein the tolerance is conferred by an imidazoleglycerol phosphate dehydratase (IGPD) tolerant of inhibition by the herbicide at levels which normally inhibit the activity of IGPD. 2. A plant of claim 1, which is maize. 3. A plant of claim 1, which is wheat or soybean. 4. A plant of claim 1, wherein the tolerance is conferred by over-expression of wild-type IGPD. 5. A plant of claim 1, wherein the tolerance is conferred by expression of a mutant IGPD. 6. A purified DNA molecule encoding plant IGPD. 7. A DNA molecule of claim 6, encoding wheat IGPD. 8. The DNA molecule of claim 7 comprising the sequence set forth in SEQ ID NO: 9. 9. A DNA molecule of claim 6, encoding Arabidopsis IGPD. 10. The DNA molecule of claim 9 comprising the sequence set forth in SEQ ID NO: 1. 11. The DNA molecule of claim 9 comprising the sequence set forth in SEQ ID NO: 12. 12. A recombinant DNA molecule, comprising a promoter capable of driving expression of an associated coding sequence in a plant cell, operably linked to a molecule of claim 6. 13. A recombinant vector, comprising a DNA molecule of claim 12, wherein said vector is capable of being stably transformed into a host cell. 14. A host cell stably transformed with a vector of claim 13, wherein said host cell is capable of expressing IGPD. 15. A host cell of claim 14, which is a plant cell, a bacterial cell, a yeast cell, or an insect cell. 16. A plant according to claim 1, wherein the tolerance is conferred by a recombinant DNA molecule according to claim 12 or 13. 17. Substantially purified IGPD. 18. IGPD according to claim 17 isolated from a higher plant. 19. IGPD according to claim 18 isolated from wheat. 20. The IGPD of claim 19 comprising the sequence for the protein as described in SEQ ID NO: 4. 21. IGPD according to claim 18 isolated from Arabidopsis. 22. The IGPD of claim 11 comprising the sequence for the protein as described in SEQ ID NO: 3. 23. Substantially purified IGPD, produced by a host cell of claim 14. 24. A method of determining the inhibitory effect on IGPD of a chemical suspected of having such an effect, comprising the steps of; (a) adding a predetermined amount of the chemical to a predetermined volume of a reaction mixture comprising substantially purified IGPD; (b) adding imidazole glycerol phosphate (IGP) to the resultant mixture to initiate an enzyme reaction; (c) terminating the reaction after a predetermined time; (d) adding alkaline phosphatase and alkali to the mixture; and (e) measuring the amount of imidazoleacetol (IA) produced by determining the absorbance difference at 370nm at an absorbance coefficient of 10,400. 25. A method of claim 24, further comprising repeating the steps, at least once, wherein in each repetition a different amount of the chemical is added to the reaction mixture. 26. A method of claim 24, wherein the IGP is synthetic. 27. A method of identifying IGPD mutants tolerant of an IGPD inhibitor comprising the steps of: (a) incubating wild-type IGPD and its substrate, IGP in the presence of an inhibitor of wild-type IGPD; (b) measuring the activity of wild-type IGPD in step (a); (c) incubating mutated IGPD and its substrate, IGP in the presence of an inhibitor of wild-type IGPD; (d) measuring the activity of mutated IGPD in step (c); and (e) comparing the activity of wild-type IGPD determined in step (b) to the activity of mutated IGPD determined in step (d). 28. A method of selecting plants, plant tissue or plant cells transformed with a transgene of interest from non-transformed plants, comprising the steps of: (a) transforming a plant, plant tissue or plant cell with a gene encoding an altered IGPD tolerant of an IGPD inhibitor; (b) transferring the thus-transformed plants or plant cells to a medium comprising the IGPD inhibitor, and (c) selecting the plants or plant cells which survive in the medium. 29. A method of claim 28, comprising the further step of transforming the plant, plant tissue or plant cell with a transgene of interest. 30. A method for the determination of IGPD in a sample, comprising the step of: measuring the amount of enolized imidazoleacetol phosphate (IAP) produced from the IGPD-catalyzed hydrolysis of IGP in the presence of alkaline phosphatase and alkali. 31. A method of claim 30, wherein said measuring comprises determining the absorption of enolized IAP at 370nm.

Inventors: IWASAKI GENJI, KOIZUMI SHINICHI, MORI ICHIRO, TADA SACHIYO, VOLRATH SANDRA, WARD ERIC R, IWASAKI, GENJI, KOIZUMI, SHINICHI, MORI, ICHIRO, TADA, SACHIYO, VOLRATH, SANDRA, WARD, ERIC, R.
Applicants: CIBA GEIGY JAPAN LTD, IWASAKI GENJI, JAPAT LTD, KOIZUMI SHINICHI, MORI ICHIRO, TADA SACHIYO, VOLRATH SANDRA, WARD ERIC R, CIBA-GEIGY JAPAN LIMITED, IWASAKI, GENJI, JAPAT LTD., KOIZUMI, SHINICHI, MORI, ICHIRO, TADA, SACHIYO, VOLRATH, SANDRA, WARD, ERIC, R.
Application year: 1994
Main classification: C12N15
IPC codes: A01H5, C12N5, C12N9, C12N15, C12Q1